A sneeze (or sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs, most commonly caused by foreign particles irritating the nasal mucosa. Sneezing can further be triggered through sudden exposure to bright light, a particularly full stomach, or as a result of unexpected, climatic variations in one's environment such as rapid changes in temperature and humidity levels.

Sneezing is widely considered to be an agent of disease dissemination in many cultures.